In the loom with the travelling-wave shed and the disk-type beat-up motion, the weft thread is propulsed by the carriers and advanced to the fell of the cloth along a line inclined towards the fell. As a result, by the moment the carrier emerges from the shed, in the extreme zone thereof there appears the excess amount of the weft thread which is determined as the difference between the length of the helical groove formed by the depressions in the disks and the width of the extreme zone. Therefore, for the normal process of the cloth formation a mechanism is required which will remove this excess amount of the weft thread from the extreme zone. Besides, the weaving practice has proven that the process of formation of the cloth edge is more stable (does not noticeably differ from the process of formation of the cloth body), if the end of the weft thread is kept taut till the end of the cloth formation process, across the entire weaving width.
When used for this purpose are the known grips stationary mounted at the exit of the carriers from the travelling-wave shed only gripping and holding of the weft thread are ensured, whereas, due to structural features of these grips, the removal of the excess amount of the weft thread under a definite tension required for producing a high-quality cloth is unattainable.
At present, there is known an apparatus for gripping the weft thread disposed next to the butt surface of the shaft of the disk-type beat-up motion at the exit of the weft thread carriers from the looming-up zone, i.e. from the traveling-wave shed and intended for gripping the weft thread behind the carrier, conveying it towards the fell of the cloth and keeping it taut by way of compensating for an excess length of the weft thread till the latter is interlaced with the warp threads of the cloth.
This apparatus includes gripping members one of which is installed displaceably relative to the other one for the weft thread to be thereby gripped. The gripping member installed stationary is made as a plate secured on the loom frame, whereas the movable gripping member is made as a bush with an engaging tooth rotating in the same direction with the disk-type beat-up motion.
The rotatable bush and the stationary plate are tightened together by a spring. In the process of gripping of the weft thread, the tooth brings the end of the weft thread to the stationary plate and, due to the mutual friction, the gripping occurs. With the engaging tooth going on displacing relative to the stationary plate, due to different coefficients of friction of the stationary plate and the tooth, the weft thread is placed under tension, i.e. the excess amount of the weft thread is withdrawn from the shed. The thread is kept taut as long as the engaging tooth interacts with the profile of the stationary plate.
However, since this apparatus depends for its operation on the friction between the thread, the stationary and the movable gripping members and also due to the lengthwise irregularity of the weft thread, the tensioning and holding thereof is unstable and deficient.
Besides, the abilities of this device to apply tension to the end of the weft thread are limited.
It is an object of the present invention to obviate the disadvantages.
The principal object of the present invention is to provide a weft thread gripping mechanism for a loom with a travelling-wave shed and a disk-type beat-up motion which should make it possible, after the weft thread is gripped and while it is transferred to the fell of the cloth, to keep it taut till it gets interlaced with the warp threads.
Another object of the present invention is to provide a weft thread gripping mechanism for a loom with a travelling-wave shed which should make it possible to improve the process of formation of the edge of the cloth.
One more object of the present invention is to produce a high-quality cloth.